<select name="aer_id" <?php echo $estilo; ?>>
    
    <option value=""><?= $t_aeronaves?></option>

    <?php
	
    $sql_aeronave = "SELECT * FROM aeronave ORDER BY aer_nome";
    $res_aeronave= sql($sql_aeronave);

    while($linha_aeronave = mysql_fetch_array($res_aeronave)){
    ?>

    <option value="<?=$linha_aeronave['aer_id'];?>" <?php if($linha_aeronave['aer_id'] == $aer_id) { echo "selected"; } ?>><?=$linha_aeronave['aer_nome'];?></option>

    <?php } ?>

</select>